Patient specific femoral prosthesis

ABSTRACT

A femoral prosthesis system for an orthopaedic hip implant and method of use is disclosed. The prosthesis system includes a femoral stem component that includes a core body and a casing that encases the core body. The casing can be additively manufactured such that the core body defines a predetermined orientation in the core body among a plurality of permissible predetermined orientations. The femoral stem component can further include a neck and a trunnion that extends from the neck. The neck can extend out with respect to the core body at a predetermined angle within a range of permissible predetermined angles.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of U.S. patent application Ser. No. 16/732,672filed Jan. 2, 2020, which is a continuation-in-part of U.S. patentapplication Ser. No. 16/587,683 filed Sep. 30, 2019, the disclosure ofwhich is hereby incorporated by reference as if set forth in itsentirety herein.

TECHNICAL FIELD

The present disclosure relates generally to customizable femoralcomponents used in a total hip arthroplasty and more particularly tofemoral implants having different core geometries within a casing thatsurrounds the core.

BACKGROUND

Joint arthroplasty is a well-known surgical procedure by which adiseased and/or damaged natural joint is replaced by a prosthetic joint.For example, in a hip arthroplasty surgical procedure, a prosthetic hipreplaces a patient's natural hip. A typical prosthetic hip includes anacetabular orthopaedic prosthesis and/or femoral head orthopaedicprosthesis. A typical acetabular orthopaedic prosthesis includes anacetabular cup, which is secured to the patient's natural acetabulum,and an associated polymer bearing or ring.

A typical femoral component includes a stem having a neck and anelongate body extending distally from the neck, and a femoral headconfigured to be positioned on the neck of the stem. The stem of thefemoral component is secured to a patient's femur. In some examples, thestem can be surrounded by an outer sleeve that defines an outer surfaceof the femoral component in the medullary canal of the femur. Thefemoral head can articulate in the acetabular cup to replicate themotion of a natural hip joint.

Examples of hip prostheses are shown and described in U.S. Pat. Nos.10,213,314 and 10,213,310

SUMMARY

According to one aspect of the disclosure, an orthopaedic systemincludes a prosthetic femoral stem and a prosthetic femoral headconfigured to engage a patient's natural acetabulum or an acetabularprosthetic component. The femoral stem includes an outer casingconfigured to engage a patient's femur. The outer casing defines alongitudinal axis that is configured to be positioned in a coronal planeof the patient's femur when the femoral stem is implanted in thepatient's femur. In some embodiments, an outer casing surface of theouter casing defines the longitudinal axis. The femoral stem alsoincludes a neck configured to receive the prosthetic femoral head toposition the prosthetic femoral head at a predetermined positionrelative to the longitudinal axis of the outer casing and/or the coronalplane. The femoral stem may be manufactured to place the neck at anumber of selectable angles to move the prosthetic femoral head in ananterior-posterior direction relative to the longitudinal axis of theouter casing and/or the coronal plane, in a medial-lateral direction,and/or in an inferior-superior direction. The selectable angles mayshift the neck anteriorly or posteriorly relative to the longitudinalaxis of the outer casing and/or the coronal plane, medially orlaterally, and/or inferiorly or superiorly. The selectable angles mayalso adjust a degree of tilt of the neck relative to the longitudinalaxis of the outer casing. The degree of tilt may cause the neck to bepivoted in any direction (anterior, posterior, medial, lateral, inferioror superior) relative to the outer casing to change the position of thefemoral head.

In one example, a femoral prosthesis includes an elongate core body thatextends along a central core body axis from a proximal core body end toa distal core body end opposite the proximal core body end. The corebody includes a medial core body side and a lateral core body sideopposite the medial core body side. The medial and lateral core bodysides extend from the proximal core body end to the distal core bodyend. The core body is configured to be received in a medullary canal ofa femur. The femoral prosthesis further includes a neck that extends outwith respect to the proximal core body end. The femoral prosthesisfurther includes a porous casing that encases at least a portion of thecore body. The porous casing defines an inner casing surface that facesthe core body and an outer casing surface opposite the inner casingsurface. The inner surface of the porous casing extends along a centralinner casing axis that is substantially coincident with the central corebody axis. The outer surface of the porous casing extends along acentral outer casing axis that intersects the central inner casing axiswithin an outer perimeter of the core body with respect to a sideelevation view of the stem component that includes the proximal corebody end and the distal core body end.

In another embodiment, a femoral prosthesis can include a core body anda casing that surrounds at least a portion of the core body. The casingcan be additively manufactured to produce a plurality of femoralprostheses that include substantially identical core bodies, but alsodefine at least one respective geometry that differs from the other ofthe femoral prostheses.

In one example, the femoral implant can include a core that includes thecore body and a neck that extends out with respect to the core body at afixed angle. The at least one respective geometry can include aselectable neck angle that is defined by a central neck axis and acentral axis of an outer casing surface of the casing. Alternatively oradditionally, the at least one geometry can include a neck offsetmeasured from the casing to the neck along a direction substantiallyparallel to the central neck axis. Alternatively or additionally still,the at least one geometry can include a rotational position of the corebody in the casing.

In another example, the casing can define an inner casing surface thatfaces the core and extends along a central inner casing axis. The corebody can extend along a core body axis that is substantially coincidentwith the central inner casing axis. The outer casing surface can extendalong a central outer casing axis that is angularly offset with respectto the central inner casing axis.

In another example, the casing can define a thickness that extends fromthe inner casing surface to the outer casing surface. The thickness canincrease in a distal direction at one of a medial side of the casing anda lateral side of the casing, and can decrease in the distal directionat the other of the medial side of the casing and the lateral side ofthe casing.

In another example, the casing can define a thickness that extends fromthe inner casing surface to the outer casing surface. The thickness canincrease in a distal direction at one of a medial side of the casing anda lateral side of the casing, and can decrease in the distal directionat the other of the anterior side of the casing and the posterior sideof the casing.

In another embodiment, a femoral prosthesis includes an elongate corebody that defines a medial core body side and a lateral core body sideopposite the medial core body side substantially along a medial-lateraldirection. The femoral prosthesis further includes a neck that extendsout with respect to the elongate core body. The femoral prosthesisfurther includes a porous casing that encases at least a portion of thecore body. The porous casing can define an inner casing surface thatfaces the core body and an outer casing surface opposite the innercasing surface. The porous casing can define an anterior casing surfaceand a posterior casing surface opposite the anterior casing surfacesubstantially along an anterior-posterior direction. The medial corebody side can define a first distance from the anterior side along theanterior-posterior direction and a second distance from the posteriorside along the anterior-posterior direction that is different than thefirst distance.

In one example, the core body can be angulated such that the medial corebody side defines a first distance from an anterior side of the casingalong an anterior-posterior direction and a second distance from aposterior side of the casing along the anterior-posterior direction thatis different than the first distance.

In another embodiment, a first femoral prosthesis and a second femoralprosthesis each define a medial side and a lateral side opposite themedial side along a medial-lateral direction, and an anterior side and aposterior side opposite the anterior side along an anterior-posteriordirection. Each of the first and second femoral prostheses include acore having a core body elongate along a core body axis, the core bodydefining an outer core body surface. The core further has a neck that ismonolithic with the core body, wherein the neck extends out with respectto the core body along a central neck axis. The core of the firstfemoral prosthesis is substantially identical to the core of the secondfemoral prosthesis. The first femoral prosthesis and the second femoralprosthesis each further include a porous casing that encases at least aportion of the core body. The porous casing defines an inner casingsurface that extends along the outer core body surface, and an outercasing surface that is opposite the inner casing surface. The outercasing surface defines a central outer casing axis. Each of the firstfemoral prosthesis and the second femoral prosthesis includes a geometrythat includes at least one of a selectable neck angle defined by thecentral neck axis and the central outer casing axis, a tilt angle alongthat is defined by the core body axis and the central outer casing axis,and a neck offset that extends from the neck to the casing along thecentral neck axis, and a rotational position of the core body relativeto the outer casing surface about an axis that substantiallyperpendicular to each of the anterior-posterior direction and themedial-lateral direction. The geometry of the first femoral prosthesisis different than the geometry of the second femoral prosthesis.

In one example, the first femoral prosthesis defines a first selectableneck angle, and the second femoral prosthesis defines a secondselectable neck angle different than the first selectable neck angle.

In another example, the first femoral prosthesis defines a first neckoffset from the casing to the neck along the central neck axis, and thesecond femoral prosthesis defines a second neck offset from the casingto the neck along the central neck axis that is different than the firstneck offset.

In another example, the core of second femoral prosthesis is rotatedabout the axis of rotation with respect to first femoral prosthesis.

In another example, the core of the first femoral prosthesis is tiltedalong the anterior-posterior direction in the outer casing of the firstfemoral prosthesis so as to define a first tilt angle, and the core ofthe second femoral prosthesis is tilted along the anterior-posteriordirection in the outer casing of the second femoral prosthesis so as todefine a second tilt angle that is different than the first tilt angle.

In another example, the casing defines an anterior casing side and aposterior casing side opposite the anterior casing side along theanterior-posterior direction, and the core body defines a medial corebody side and a lateral core body side opposite the medial core bodyside. The medial core body side of the second femoral prosthesis can bespaced further from the anterior casing side than the medial core bodyside of the first femoral prosthesis is spaced from the anterior casingside.

Each of the first femoral prosthesis and the second femoral prosthesiscan further include a collar that extends at least medially out withrespect to the outer core body surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the following figures,in which:

FIG. 1 is an exploded perspective view of a femoral prosthesis

FIG. 2A is a sectional elevation view of the femoral prosthesisillustrated in FIG. 1 , taken along line 2A-2A;

FIG. 2B is a sectional elevation view of a femoral prosthesis similar tothe femoral prosthesis illustrated in FIG. 2A, but showing a differentneck angle;

FIG. 3 is an exploded perspective view of a femoral prosthesis similarto the femoral prosthesis illustrated in FIG. 1 ;

FIG. 4 is a perspective view of a portion of a porous casing of thefemoral prosthesis illustrated in FIGS. 1 and 3 ;

FIG. 5 is an exploded perspective view of the femoral prosthesisillustrated in FIG. 1 , further showing a plurality of collars;

FIG. 6A is a sectional elevation view of the femoral prosthesisillustrated in FIG. 1 , showing one of the collars of FIG. 5 attached tothe core;

FIG. 6B is a sectional elevation view of the femoral prosthesisillustrated in FIG. 1 , showing a collar monolithic with the casing;

FIG. 6C is a sectional elevation view of the femoral prosthesisillustrated in FIG. 1 , showing a collar monolithic with the core;

FIG. 7A is a sectional side elevation view of a portion of the femoralprosthesis illustrated in FIG. 1 , wherein the stem component defines afirst selectable neck angle;

FIG. 7B is a sectional side elevation view of the femoral prosthesisillustrated in FIG. 7A, but wherein the stem component defines a secondselectable neck angle;

FIG. 7C is a sectional elevation view of the femoral prosthesisillustrated in FIG. 1 , wherein the stem component defines a neutralselectable neck angle position

FIG. 8A is a sectional side elevation view of a portion of the femoralprosthesis illustrated in FIG. 1 , wherein the stem component defines afirst tilt position;

FIG. 8B is a sectional side elevation view of the femoral prosthesisillustrated in FIG. 8A, but wherein the stem component defines a secondtilt position different than the first tilt position;

FIG. 8C is a sectional elevation tilt angle view of the femoralprosthesis illustrated in FIG. 1 , wherein the stem component defines athird neutral tilt position;

FIG. 9A is a sectional plan view of the femoral prosthesis illustratedin FIG. 1 , wherein the stem component defines a first rotationalposition;

FIG. 9B is a sectional side elevation view of the femoral prosthesisillustrated in FIG. 8A, but shown wherein the stem component defines asecond rotational position different than the first rotational position;

FIG. 9C is a sectional side elevation view of the femoral prosthesisillustrated in FIG. 8B, but shown wherein the stem component defines athird neutral rotational position;

FIG. 10A is a sectional plan view of the femoral prosthesis illustratedin FIG. 1 , wherein the stem component defines a first neck offset;

FIG. 10B is a sectional side elevation view of the femoral prosthesisillustrated in FIG. 10A, but shown wherein the stem component defines asecond neck offset; and

FIG. 11 is a simplified block diagram of a method for implanting afemoral prosthesis illustrated in FIG. 1 .

DETAILED DESCRIPTION

While the concepts of the present disclosure are susceptible to variousmodifications and alternative forms, specific exemplary embodimentsthereof have been shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit the concepts of the present disclosure tothe particular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.Further, the term “at least one” stated structure as used herein canrefer to either or both of a single one of the stated structure and aplurality of the stated structure.

While the concepts of the present disclosure are susceptible to variousmodifications and alternative forms, specific exemplary embodimentsthereof have been shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit the concepts of the present disclosure tothe particular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

References in the specification to “one embodiment”, “an embodiment”,“an example embodiment”, etc., indicate that the embodiment describedmay include a particular feature, structure, or characteristic, butevery embodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to effect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed.

Referring to FIGS. 1-2A, a femoral prosthesis 10 of a hip prosthesisincludes a femoral stem component 16 that is configured to be implantedinto the medullary canal 21 of a patient's femur 23. The femoralprosthesis 10 can further include a head component 18 that is configuredto attach to the femoral stem component 16. The head component 18 candefine an outer articulation surface 25 that is configured to articulatealong a complementary bearing surface of an acetabular prostheticcomponent that is implanted in the patient's acetabulum. In one example,the outer articulation surface 25 can be three-dimensionally curved. Forinstance, the outer surface can be substantially spherically shaped. Anacetabular prosthetic component generally includes an outer shellconfigured to engage the acetabulum of the patient and an inner bearingor liner coupled to the shell that is configured to engage the femoralhead component 18 to form a ball and socket joint that approximates thenatural hip joint.

The femoral prosthesis 10 can define a medial side 11 and a lateral side13 opposite the medial side 11 along a medial-lateral direction. Thus,the femoral prosthesis 10, and the elements thereof, defines a medialdirection that is oriented from the lateral side 13 to the medial side11, and a lateral direction that is oriented from the medial side 11 tothe lateral side 13. The femoral prosthesis can further include ananterior side 15 and a posterior side 27 opposite the anterior side 15along an anterior-posterior direction that is substantiallyperpendicular to the medial-lateral direction. Thus, the femoralprosthesis 10, and the elements thereof, defines an anterior directionthat is oriented from the posterior side 27 to the anterior side 15, anda posterior direction that is oriented from the anterior side 15 to theposterior side 27. The anterior and posterior sides 15 and 27 eachextend from the medial side 11 to the lateral side 13. Similarly, themedial and lateral sides each extend from the anterior side 15 to theposterior side 27.

Unless otherwise indicated herein, the term “substantially,”“approximately,” and derivatives thereof, and words of similar import,when used to describe a size, shape, angle orientation, distance,spatial relationship, or other parameter includes the stated size,shape, angle, orientation, distance, spatial relationship, or otherparameter, and can also include a range up to 10% more and up to 10%less than the stated parameter, including 5% more and 5% less, including3% more and 3% less, including 1% more and 1% less. The term“substantially” in the context of substantially perpendicular axisincludes perpendicular, and can also include up to +/−25 degrees fromperpendicular. The term “substantially identical” and derivativesthereof as used herein refer to being designed to be identical in sizeand shape, and thus within manufacturing tolerances. Thus, the term“different” when used in connection with a comparison to differentsizes, orientations, angles, shapes, or other value means that thecompared values are different than each other by design, and thusoutside of manufacturing tolerances.

The femoral prosthesis 10 can further include a collar 14 that extendsmedially outward from the femoral stem component 16. In other examples,the femoral stem component 16 can include the collar 14. In use, anorthopaedic surgeon may assemble a femoral prosthesis 10 using thevarious components before implanting the assembled femoral prosthesis 10in the patient's femur 23. For example, in some patients, the femoralprosthesis 10 may include only the stem component 16 and the femoralhead component 18. For other patients, the orthopaedic surgeon maycouple one of the collar 14 to the stem component 16 to address specificadditional needs of a patient.

The stem component 16 defines a medial side 42 and a lateral side 44opposite the medial side 42 substantially along a medial-lateraldirection. The medial and lateral sides 42 and 44 of the stem component16, respectively, define respective portions of the medial and lateralsides 11 and 13, respectively, of the femoral prosthesis. The stemcomponent 16 further defines an anterior side 46 and a posterior side 48opposite the anterior side 46 substantially along an anterior-posteriordirection. The anterior and posterior sides 46 and 46, respectively, ofthe stem component 16 define a portion of the anterior and posteriorsides 15 and 27, respectively, of the femoral prosthesis 10. Theelements of the stem component 16 described below can similarly definerespective anterior and posterior sides. The medial side 42 and thelateral side 44 are spaced from each other a first distance, and theanterior side 46 and the posterior side 48 are spaced from each other asecond distance that is less than the first distance.

The stem component 16 can include an elongate core body 34 and a neck 28that extends out with respect to the elongate core body 34. Forinstance, the neck 28 can extend out from the core body 34. The corebody 34 can thus extend distally from the neck 28. Alternatively, thestem component 16 can further include a shoulder 32 that is disposedbetween the core body 34 and the neck 28. Thus, the neck 28 can extendout from the shoulder 32 that, in turn, extends out from the core body34. Further, the core body 34 can extend distally from the shoulder 32.Either way, it can be said that the core body 34 extends distally withrespect to the neck 28. The core body 34 is configured to be received inthe medullary canal 21 of the patient's femur 23. The neck 28 can extendout with respect to the core body 34 at a fixed neck angle 40.

The neck 28 includes a trunnion 30 that extends superiorly and medially.The stem component 16 can define a proximal end 17. The proximal end 17can be defined by the trunnion 30 in some examples. The trunnion 30 isconfigured to attach to the femoral stem component 16. The trunnion 30is shaped to receive the femoral head component 18 by being positionedin a matching bore (not shown) of the femoral head component 18. Thebore and the trunnion 30 can have matching tapers such that the femoralhead component 18 may be secured to the stem component 16 via a Morsetaper locking connection. In other embodiments, the trunnion 30 and thesurface lining the bore of the femoral head component 18 may bethreaded.

The core body 34 can extend distally to a distal core body end 37 of thecore body 34. The stem component 16 can further include a casing 33 thatencases at least a portion of an entire length of the core body 34. Inthe illustrative embodiment, the core body 34 and the surrounding casing33 are shaped to be received in the medullary canal 21 patient's femur23 via a press-fit to secure the stem component 16, to the patient'sfemur 23. In other embodiments, the core body 34 and the surroundingcasing 33 may be secured to the femur 23 via other attachment means suchas, for example, bone cement. The stem component 16 can define a distalend 19 that is opposite the proximal end 17. The distal end 19 of thestem component 16 can be defined by the casing 33 in some examples. Inother examples, for instance whereby the casing does not extend alongthe entire length of the core body 34, the distal end of the stemcomponent 16 can be defined by the casing 33. Thus, the stem component16, the core body 34, and the casing 33 can define a proximal directionfrom the distal end 19 to the proximal end 17. Conversely, the stemcomponent 16, the core body 34, and the casing 33 can define a distaldirection from the proximal end 17 to the distal end 19.

As will be described in more detail below, the casing 33 extends over atleast a portion of the core body 34. Thus, the casing 33 defines aninner casing surface 108 that faces an outer core body surface 109 ofthe core body 34, the casing 33, and an outer casing surface 110opposite the inner casing surface 108. The casing 33 can be additivelymanufactured so as to encase the core body 34. For instance, the casing33 can be additively manufactured onto the core body 34 so as to definea coating having an inner casing surface 108 that extends along theouter core body surface 109. Accordingly, the inner casing surface 108can be coated onto the outer core body surface 109 after the casing hasbeen additively manufactured onto the core body 34. Thus, the innercasing surface 108 can face the outer core body surface 109.Alternatively, as illustrated in FIG. 3 , the casing 33 can beadditively manufactured as a separate component 61 that is sized andconfigured to receive the core body 34. Thus, the casing 33 of theseparate component 61 defines the inner casing surface 108 prior toattaching the casing 33 to the core body 34. The inner casing surface108 of the casing 33 of the separate component 61 faces the core body 34when the casing 33 receives the core body 34. Whether the casing 108 isadditively manufactured onto the core body 34 or additively manufacturedas the separate component 61, it can be said that the casing 33 encasesat least a portion of the core body 34. The neck 28 can extend out withrespect to the elongate core body 34. For instance, the neck 28 canextend out from the core body 34. Alternatively, the elongate body 34can include the shoulder 32 that extends from the inner core body 34,such that the neck extends out from the shoulder 32.

Referring again to FIGS. 1-2B, the core body 34 can define a proximalcore body end 35 and a distal core body end 37 opposite the proximalcore body end 35. The proximal core body end 35 can be disposed at aninterface between the core body 34 and the shoulder 32. Alternatively,in instances whereby the stem component 16 does not include theshoulder, the proximal core body end 35 can be disposed at an interfacebetween the core body 34 and the neck 28. The core body 34 can define adistal core body end 37 opposite the proximal core body end 35 along acentral core body axis 39. Thus, the elongate core body 34 can beelongate along the central core body axis 39 from a proximal core bodyend 35 to the distal core body end 37.

Referring again to FIGS. 1-2A, the distal core body end 37 can be spacedfrom the distal end 19 of the stem component in the proximal direction.For instance, the casing 33 can define a distal casing end 49 that isdisposed distal of the distal core body end 37. The central core bodyaxis 39 extends through the core body 34 from the proximal core body end35 to the distal core body end 37. The central core body axis 39 extendscentrally through the core body 34 with respect to a medial core bodyside 54 of the core body 34 and a lateral core body side 56 of the corebody 34. The medial core body side 54 and the lateral core body side 56can be opposite each other substantially along the medial-lateraldirection. The medial core body side 54 and the lateral core body side56 each extend from the proximal core body end 35 to the distal corebody end 27. The medial core body side 54 and the lateral core body side56 can define a portion of the medial side 42 and a lateral side 44 ofthe stem component 16. That is, the central core body axis 39 can extendcentrally through the core body 34 with respect to a side elevation viewof the core body 34 that includes the medial core body side 54 and thelateral core body side 56. Further, the central core body axis 39 can becentrally disposed with respect to the anterior and posterior sides,respectively, of the core body 34. The medial and lateral core bodysides 54 and 56 can extend from the side and the posterior side of thecore body 34.

The core body 34 can further include an anterior core body side 57 and aposterior core body side 59 (see FIGS. 9A-9C). The anterior core bodyside 57 and the posterior core body side 59 can be opposite each othersubstantially along the anterior-posterior direction that issubstantially perpendicular to the medial-lateral direction. Theanterior core body side 57 and the posterior core body side 59 candefine respective portions of the anterior side 46 and a posterior side48 of the stem component 16, for instance at locations of the core body34 that protrude from the casing 33. In one example, such locations canbe at a superior end of the core body 34 that defines the proximal corebody end 35. The anterior core body side 57 and the posterior core bodyside 59 can extend from the medial core body side 54 to the lateral corebody side 56.

The central core body axis 39 can define any suitable shape depending onthe design of the core body 34. For instance, the central core body axis39 can be curved in one example. The central core body axis 39 can havea constant curvature. Alternatively, the central core body axis 39 canhave curvatures that vary along its length. Alternatively, the centralcore body axis 39 can be straight and linear. Alternatively still, thecentral core body axis 39 can include a plurality of straight and linearsegments that are angled with respect to each other. Alternativelystill, the central core body axis 39 can include one or more straightand linear segments and one or more curved segments.

The casing 33 can also define a first or medial casing side 70 and asecond or lateral casing side 72. The medial casing side 70 and thelateral casing side 72 are opposite each other along the medial-lateraldirection. The medial and lateral casing sides 70 and 72, respectively,of the casing 33 can define at least a portion of the medial and lateralsides 42 and 44, respectively, of the stem component 16. The outercasing surface 110 at the medial and lateral casing sides 70 and 72 cantaper toward each other as they extend distally.

The casing 33 can further include an anterior casing side 71 and aposterior casing side 73. The anterior casing side 71 and the posteriorcasing side 73 can be opposite each other substantially along theanterior-posterior direction that is substantially perpendicular to themedial-lateral direction. The anterior casing side 71 and the posteriorcasing side 73 can define respective portions of the anterior side 46and a posterior side 48 of the stem component 16. The anterior casingside 71 and the posterior casing side 73 can extend from the medialcasing side 70 to the lateral casing side 72.

In one example, the neck 28 can extend out from the core body 34 so asto define an inner core 31. For instance, the neck 28 can be monolithicwith the core body 34 so as to define the inner core 31, which can be asingle unitary structure. The inner core 31 can further include thetrunnion 30. The trunnion 30 can be monolithic with the neck 28 and thecore body 34. The inner core 31 can further include the shoulder 32. Theshoulder 32 can be monolithic with the trunnion 30, the neck 28, and thecore body 34 so as to define the inner core 31. Thus, the inner core 31can be a single monolithic structure. Thus, it should be appreciatedthat the casing 33 can encapsulate at least a portion of an overalllength of the core 31 as defined from the distal core body end 37 to theproximal end 17 of the trunnion 30. In one example, the inner core 31can be made of any suitable biocompatible material, such as a metal.Further, the inner core 31, including the core body 34, the neck 28, thetrunnion 30, and the shoulder 32, can be a forged metal. In one example,the inner core 31 can be made of stainless steel, cobalt chromium,titanium, tantalum, niobium, or alloys thereof. It is recognized, ofcourse, that the inner core 31 can be made of any suitable alternativematerial, and fabricated using any suitable fabrication method asdesired.

Referring now to FIGS. 2A-2B, the neck 28 can extend out with respect tothe core body 34, and in particular the proximal core body end 35, alonga central neck axis 29 that combines with the central core body axis 39to define any desirable fixed neck angle 40 with respect to a sideelevation view of the stem component 16 that includes the distal end 19of the stem component 16, the proximal end 17 of the stem component 16,the medial side 42 of the stem component 16, and the lateral side 44 ofthe stem component 16. For instance, the neck 28 can extend out from theproximal core body end 35. Alternatively, the shoulder 32 can bedisposed between the proximal core body end 35 and the neck 28. Thus,the neck 28 can extend out from the shoulder 32 that, in turn, extendsout from the proximal core body end 35. Because the neck 28 and the corebody 34 can be monolithic with each other, or otherwise secured to thecore body 34, the neck angle 40 can be referred to as a fixed neckangle. That is, the fixed neck angle 40 cannot be altered withoutredesigning the core 31. In one example, the central neck axis 29 can becoplanar with the central core body axis 39 such that the axes 29 and 39intersect each other so as to define the fixed neck angle 40.Alternatively, the central neck axis 29 and the central core body axis39 can be non-coplanar with each other. Either way, the axes 29 and 39intersect each other with respect to a side elevation view of the stemcomponent 16 that includes the distal end 19 of the stem component 16,the proximal end 17 of the stem component 16, the medial side 42 of thestem component 16, and the lateral side 44 of the stem component 16.Further, because the inner casing surface 108 of the casing 33 canextend along the outer core body surface 109 of the core body 34,central neck axis 29 and the central inner casing axis 112 can definethe angle 40. FIG. 2A illustrates the neck 28 extending out from thecore body 34 at a first fixed neck angle 40. FIG. 2B illustrates theneck 28 extending out from the core body 34 at a second fixed neck angle40 different than the first fixed neck angle 40.

The inner casing surface 108 can extend along a central inner casingaxis 112. For instance, the inner casing surface 108 can be elongatealong the central inner casing axis 112. The central inner casing axis112 extends centrally through the casing 33 at a location centrallydisposed with respect to the inner casing surface 108. For instance, thecentral inner casing axis 112 extends centrally through the casing 33 ata location centrally disposed with respect to the inner casing surface108 at the medial casing side 70 and the inner casing surface 108 at thelateral casing side 72. That is, the central inner casing axis 112extends through the casing 33 at a location centrally disposed withrespect to the inner casing surface 108 along a sectional side elevationview of the casing 33 that includes the medial casing side 70 and thelateral casing side 72. Further, the central inner casing axis 112 canbe centrally disposed with respect to the anterior casing side 71 andthe and posterior casing side 73. Thus, it can be said that the innercasing surface 108 at the medial casing side 70 and the lateral casingside 72 combine to at least partially define the central inner casingaxis 112. It can also be said that the inner casing surface 108 at theanterior casing side 71 and the posterior casing side 73 can alsocombine to partially define the central inner casing axis 112. Becausethe casing 33 can be coated onto the outer core body surface 109, thecentral inner casing axis 112 can be substantially coincident with thecentral core body axis 39. Thus, the fixed neck angle 40 can be definedby the central neck axis 29 and either or both of the central innercasing axis 112 and the central core body axis 39.

It is recognized that either or both of the central neck axis 29 andeither or both of the central core body axis 39 and the central innercasing axis 112 can be curved where they intersect. Thus, the neck angle40 can be measured by respective tangents to the central neck axis 29,the central core body axis 39, and the central inner casing axis 112where they intersect, when the axes are curved where they intersect. Inthis regard, all angles disclosed herein defined by one or more curvedaxes can be measured by respective tangents of the one or more curvedaxes where the axes intersect. The central neck axis 29 can becoincident with a central axis of the trunnion axis. Alternatively, thetrunnion 30 can be oriented such that the central axis of the trunnionis angularly offset with respect to the central neck axis 29.

As described above, the core body 34 extends along an overall lengthfrom the proximal core body end 35 to the distal core body end 37. Thecasing 33 can encase at least a portion of the overall length of thecore body 34 up to an entirety of the overall length of the core body 34from the proximal core body end 35 to the distal core body end 37. Inparticular, the casing 33 can surround the core body 34 along a planethat is oriented perpendicular to the central core body axis 39.Further, in some examples, the casing 33 can encapsulate the distal corebody end 37. Thus, the distal casing end 49 can be disposed distal ofthe distal core body end 37. Further, the distal end 19 of the stemcomponent 16 can be defined by the distal casing end 49. Alternatively,the casing 33 can terminate proximal of the distal core body end 37,such that the distal casing end 49 is spaced from the distal core bodyend 37 in the proximal direction. The casing 33 can further define aproximal casing end 51 opposite the distal casing end 49. The proximalcasing end 51 can terminate at the shoulder 32 in some examples. Thus,the casing 33 can extend in the distal direction from the shoulder 32 tothe distal casing end 49. In the event that the inner core 31 does notinclude the shoulder 32, the casing 33 can extend in the distaldirection from the neck 28 to the distal casing end 49. In otherexamples, the casing 33 can extend to a location proximal of the neck28. For instance, the casing 33 can encapsulate an entirety of the core31. Thus, in this example, the proximal casing end 51 can define theproximal end 17 of the stem component 16.

As described above, the casing 33 can be additively manufactured. In oneexample, the casing 33 can be made of a porous material 53 as describedin U.S. patent application Ser. No. 16/365,557 filed Mar. 26, 2019, thedisclosure of which is hereby incorporated by reference as if set forthin its entirety herein. Because the casing 33 is made of the porousmaterial 53, the casing 33 can be referred to as a porous casing.Additive manufacturing processes can include, by way of example, powderbed fusion printing, such as melting and sintering, cold spray 3Dprinting, wire feed 3D printing, fused deposition 3D printing, extrusion3D printing, liquid metal 3D printing, stereolithography 3D printing,binder jetting 3D printing, material jetting 3D printing, and the like.

In one example, referring to FIG. 4 , the porous material 53 of thecasing 33 can be defined by a porous three-dimensional structure thatcan comprise a plurality of connected unit cells. Each unit cell candefine a unit cell structure 200 that includes a plurality of latticestruts 210 and a plurality of internal structs 220 so as to define afirst geometric structure 230 and a plurality of second geometricstructures 240 that are disposed within the first geometric structure230. In one example, the first geometric structure 230 can include theplurality of lattice struts 210. The lattice struts 210 cooperate todefine the first geometry. Each of the plurality of second geometricstructures 240 can define an internal volume that is substantially equalto the internal volumes of the other second geometric structures 240.Each second geometric structure 240 can be formed by a plurality of theinternal struts 220 and a plurality of the lattice struts 210. In oneexample, the first geometric structure can be a rhombic dodecahedron,and the second geometric structure can be a rhombic trigonaltrapezohedron. It should be appreciated, of course, that the first andsecond geometric structures can vary as desired. Further, it should beappreciated that the unit cells that make up the casing 33 can have anysuitable alternative geometry as desired.

The porous material 53 can be a metal powder that can be used to formthe casing 33. In one example, the metal powders can include, but arenot limited to, titanium, titanium alloys, stainless steel, cobaltchrome alloys, tantalum, or niobium powders. As illustrated in FIGS.2A-2B, the porous material 53 can have a porosity suitable to facilitatebony ingrowth into the femoral prosthesis 10 when the core 31 isdisposed in the medullary canal 21, but can be sufficiently solid suchthat the femoral prosthesis 10 has a desired rigidity. It isappreciated, of course, that the porous material can be any suitablealternative biomedical material. For instance, the porous material 53can be a powder that can be used to form the casing 33. In one example,the powder can be a metallic powder. Alternatively, the powder can be apolymeric powder, such as polyetheretherketone (PEEK). For instance, thePEEK can be a composite-reinforced PEEK. The composite has an elasticmodulus of approximately 21.5 GPa and an ultimate tensile strength ofapproximately 223 MPa. Thus, the casing 33 has an elastic modulus thatis similar to that of a patient's femur. In other embodiments, thecasing 33 can be formed of any suitable composite or polymeric materialhaving a low elastic modulus, such as, for example, a glass-filledpolymer such as glass-filled PEEK, a non-reinforced polymer such as neatPEEK, or any other suitable reinforced or non-reinforced polymer.

In one example, the casing 33 can be additively manufactured directlyonto at least a portion of the core body 34 so as to define a porouscoating 50 that surrounds the core body 34. Alternatively, asillustrated in FIG. 3 , the casing 33 can be manufactured as a separatesleeve 52 that can be coupled to the inner core 31. In particular, thesleeve 52 can define an internal void 55 that receives the inner core31, such that the casing 33 surrounds at least a portion of the core 31in the manner described herein. The sleeve 52 can be adhesively attachedto the inner core 31 or attached using any suitable mechanical devicesuch as one or more screws or other fasteners.

Referring now to FIG. 5-6C generally, and as described above, thefemoral prosthesis 10 can further include one of a plurality of collars14. For instance, referring now to FIGS. 5 and 6A, the collars 14 caninclude a stabilizing collar 22 and a trochanter collar 24 that may beselectively secured to the femoral stem component 16. As described ingreater detail below, each collar 14 is configured to be coupled to thestem component 16 in a fixed, immoveable position relative to the stemcomponent 16. Alternatively, the collar 14, including one of thestabilizing collar 22 and the trochanter collar 24, can be monolithicwith the inner core 31 or the casing 33. When the femoral prosthesis 10is implanted in the patient's femur 23, the collar 14 is configured toengage the patient's femur 23 to provide additional stability for thefemoral prosthesis 10. It should be appreciated that in otherembodiments the plurality of collars 14 of the femoral prosthesis 10 mayinclude additional collar configurations, including collars of differentsizes and shapes.

In an illustrative embodiment, each collar 14 can formed from aresorbable material that may be assimilated into the body over time. Inthe one example, each collar 14 can be made of a rigid polymer such aspolyetheretherketone (PEEK). The collar 14 can be additivelymanufactured as described above with respect to FIG. 4 . Thus, thecollar 14 can be a porous PEEK. As a result, each collar 14 is capableof providing more stability than a stem component 16 alone and is easierto manipulate in the event that a revision hip replacement is necessary.In other embodiments, one or more of the collars 14 may be formed from amedical-grade metallic material such as stainless steel, cobalt chrome,or titanium, although other metals or alloys may be used. In thisregard, the collar 14 can be made from the same material as the casing33. Thus, the collar 14 can be referred to as a porous collar. Further,the collar 14 can be additively manufactured as described herein withrespect to the casing 33.

Referring to FIG. 5-6A, the shoulder 32 can be configured to be securedto one of the collars 14. For instance, the stem component 16 includes agroove 88 that is formed at least in the anterior side and the posteriorside of the stem component 16. The groove 88 can be defined at theshoulder 32 or any suitable alternative location of the stem component16. The groove 88 can be sized to receive portions of the collar 14 tosecure the collar 14 to the stem component 16 via a press-fit or othersuitable mechanical connection.

The collar 14 can include one of a stabilizing collar 22 and atrochanter collar 24 in one example. Each of the collars 22 and 24 isconfigured to engage a surgically prepared proximal surface 90 of thepatient's femur 23 (see FIGS. 2A-2B) when the femoral prosthesis 10 ispositioned in the patient's femur 23. In other embodiments, however, thetrochanter collar 24 may not engage the surgically prepared proximalsurface of the patient's femur 23 and may be configured to only engage aportion of the patient's trochanter.

For instance, each of the collars 22 and 24 can include a base 94 thatis configured to attach to the stem component 16. The base 94 isconfigured to be received in the groove 88. The base 94 defines anaperture 96 that is configured to receive the stem component 16, suchthat at least one inner wall 95 of the base 94 that at least partiallydefines the aperture 96 is received in the groove 88 of the stemcomponent 16.

The stabilizing collar 22 can define an opening formed at a lateral endof its base 94 so as to define a pair of arms 97 and 99 that are spacedfrom each other. Thus, the arms 97 and 99 can combine to define the atleast one inner wall 95 that is received in the groove 88 to couple thestabilizing collar 22 to the stem component 16. The aperture 96 definesan open-ended slot 101 between the arms 97 and 99 that is configured toreceive the stem component 16 as the stabilizing collar 22 is movedalong the lateral direction so as to receive the stem component 16 inthe slot 101.

The illustrative aperture 96 of the trochanter collar 24 can define aclosed through-hole 105 that extends through its base 94. Thethrough-hole 105 can be defined by the inner wall 95 of the trochantercollar 24. The through hole 105 can receive the stem component 16 alongone of the proximal direction and the distal direction. The inner wall95 can ride along the stem component 16 until the inner wall 95 isresiliently forced into the groove 88 of the stem component 16, therebysecuring the trochanter collar 24 to the stem component 16.

The stabilizing collar 22 can further include an abutment member 102that extends medially out from the base 94. Thus, the abutment member102 can further extend out with respect to the neck 28 in any suitablepredetermined direction. For instance, the abutment member 102 canextend medially out with respect to the neck 28. The abutment member 102can be substantially coplanar with the base 94. The abutment member 102can define an inferior surface 103 that is configured to abut thesurgically prepared proximal surface 90 of the patient's femur 23 duringuse.

The trochanter collar 24 can be configured as a calcar attachment, andcan further include an abutment member 104 that extends out from thebase 94. For instance, the abutment member 104 can extend away from thebase 94 along any suitable predetermined direction and cooperates withthe base 94 so as to define a non-orthogonal angle 117. When thetrochanter collar 24 is coupled to the stem component 16, the abutmentmember 104 extends medially and superiorly out with respect to the neck28. The abutment member 104 of the trochanter collar 24 can define aninferior surface 103 that is configured to abut the surgically preparedproximal surface 90 of the patient's femur 23 during use. It should beappreciated that the aperture 96 of the stabilizing collar 22 canalternatively define a through-hole, and the aperture 96 of thetrochanter collar 24 can alternatively define an open-ended slot.

In still other examples, such as is shown in FIG. 6B, the collar 14 canbe monolithic with one the casing 33. Alternatively still, asillustrated in FIG. 6C, the collar 14 can be monolithic with the innercore 31. Alternatively still, as illustrated in FIG. 10A, the femoralprosthesis 10 can be devoid of a collar.

As will now be described with reference to FIGS. 7A-10B, a plurality(i.e., greater than one) of different femoral prostheses 10, such asfirst and second femoral prostheses, can be fabricated from the samecore 31. The femoral prostheses 10 can further be customized fordifferent patients. For instance, the femoral prostheses can define atleast one respective geometry that differs from the other of the femoralprostheses.

As illustrated in FIGS. 7A-7C, the geometry can include a selectableneck angle 162. Thus, while the fixed neck angle 40 can be the same forthe first and second femoral prosthesis 10, the selectable neck angle162 of a first femoral prosthesis 10 can be different than theselectable neck angle 162 of a second femoral prosthesis 10. Theselectable neck angle 162 can be different than the fixed neck angle. Asillustrated in FIG. 7A, a first femoral implant 10 defines a firstselectable neck angle 162 a. As illustrated in FIG. 7B, a second femoralimplant 10 defines a second selectable neck angle 162 a. As illustratedin FIG. 7C, a third femoral implant 10 defines a neutral selectable neckangle position having a third selectable neck angle that is differentthan each of the first and second selectable neck angles. The term“selectable” in connection with any of the geometries described herein,including the neck angle, indicate a geometry within a range ofpermissible geometries for the femoral prosthesis 10.

Alternatively or additionally, as illustrated in FIGS. 8A-8C, thegeometry can include a tilt angle 165 of the core body 34, and thus ofthe core 31, with respect to the outer casing 33 along theanterior-posterior direction. In particular, as illustrated in FIG. 8A,the inner core 31 of a first femoral prosthesis 10 can define a firsttilt position along the anterior-posterior direction relative to theouter casing surface 110. As illustrated in FIG. 8B, the inner core 31of a second femoral prosthesis 10 can define a second tilt positionalong the anterior-posterior direction relative to the outer casingsurface 110. The second tilted position can be different than the firsttilted position. Thus, the first tilted position can be defined by afirst tilt angle 165 a, and the second tilted position can be defined bya second tilt angle 165 b that is different than the first tilt angle165 a. As illustrated in FIG. 8C, the inner core 31 of a third femoralprosthesis can define a third tilt position along the anterior-posteriordirection relative to the outer casing surface 110. The third tiltposition can be a neutral position of the inner core with respect to theouter casing surface 110. As described herein, the outer casing surface110 of each of the first, second, and third femoral implants can besubstantially identical to each other. It is appreciated that the tiltpositions and corresponding tilt angles

Alternatively or additionally still, referring to FIGS. 9A-9C, thegeometry can include a rotational position 166 of the core body 34, andthus of the core 31. In particular, the inner core 31 can define arotational position 166 relative to the outer casing surface 110 aboutan axis of rotation 167 that is oriented in a directed substantiallyperpendicular to each of the medial-lateral direction and theanterior-posterior direction. Accordingly, the rotational positions 166can be defined in a plane that defined by the anterior-posteriordirection and the medial-lateral direction. The first femoral prosthesis10 can define a first rotational position 166 a, and the second femoralprosthesis 10 can define a second rotational position 166 b that isdifferent than the first rotational position 166 a.

Alternatively or additionally yet, as illustrated in FIGS. 10A-10B, thegeometry can include a neck offset 164. The neck offset 164 extends fromthe core 31 to the neck 28 substantially along the central neck axis 29.Thus, the first femoral prosthesis 10 can define a first neck offset 164a, and the second femoral prosthesis 10 can define a second neck offset164 b that is different than the first neck offset. As will be describedin more detail below, each of the geometries can determine at least oneor both of a position and an orientation of the neck 28 with respect tothe outer casing surface 110.

Referring again to FIGS. 7A-10B generally, because the trunnion 30 canextend out from the neck 28 at a fixed position with respect to the neck28, each of the geometries of the femoral prosthesis 10 described hereincan further determine at least one or both of a position and orientationof the neck 28 with respect to the outer casing. Further still, becausethe head component 18 can be coupled to the trunnion 30, each of thegeometries of the femoral prosthesis 10 described herein can furtherdetermine a position of the head component 18, and an orientation of thestem component 16 with respect to the head component 18 when the headcomponent is received by the acetabular prosthesis.

While first and second femoral prostheses 10 having a different one ormore up to all of the geometries are used as examples, but it should beappreciated that a plurality of femoral prostheses 10 can have one ormore up to all different geometries. Thus, it will be appreciated that aplurality of femoral prostheses 10 can be constructed usingsubstantially identical inner cores 31 and can still be customized tobetter fit different specific patient anatomies. The femoral prosthesis10 can be referred to as a patient specific femoral prosthesis. Forlarge differences in patient anatomies greater than the differenceattained by the geometries described herein, as can occur in patientshaving significant age differences and gender differences, cores 31 ofthe type described herein can be produced having different sizes.However, the ability for the resulting femoral prosthesis to have atleast one of the geometries can result in a reduced number of stockkeeping units (SKU) of the inner core 31 while allowing the femoralprosthesis 10 to accommodate a greater number of different patientanatomies that are currently accommodated using a greater number of SKUsthan previously achieved. Further, in some examples, the outer casingsurface 110 of the femoral prostheses 10 can have substantially the samesize and substantially the same shape, such that femoral prostheses 10having substantially the same size and shaped cores 31 can also definesubstantially the same size and shaped prosthesis 10.

It is recognized that each femoral prosthesis 10 can be fabricated for aspecific patient anatomy. Thus, an orthopaedic implant system caninclude a plurality of femoral prostheses 10 that can be produced atdifferent times, including a first femoral prosthesis and a secondfemoral prosthesis that is different than the first femoral prosthesis.The different prostheses 10 of the orthopedic implant system can beproduced non-contemporaneously. For instance, different femoralprostheses 10 can be fabricated days, weeks, months or even years apart.Further, the femoral prostheses 10 of the orthopedic implant system canbe packaged and delivered separately to different healthcare providers.Therefore, it is recognized that the plurality of femoral prostheses ofthe orthopedic implant system can be produced that are not provided in asingle kit in some examples. In other examples, it is recognized that aplurality of the femoral prostheses 10 described herein of theorthopedic implant system can be provided in a kit, such that ahealthcare provider can have an inventory of the femoral prostheses 10with one or more different respective geometries among the plurality ofrespective geometries described herein.

Referring now to FIGS. 7A-7C in particular, and as described above, thefemoral prosthesis, can include a selectable neck angle 162 with respectto the casing 33. Thus, the neck 28 can extend out from the core body 34both at the fixed neck angle 40 and at the selectable neck angle 162. Aswill now be described, the outer casing 33 can define the selectableneck angle 162. For instance, the outer casing 33 can be fabricated suchthat the core 31, and thus the neck 28, can define any suitableselectable orientation with respect to the outer casing.

The outer casing surface 110 of the casing 33 can extend along alongitudinal axis of the casing 33 that is the central outer casing axis114. For instance, the outer casing surface 110 can be elongate alongthe central outer casing axis 114. The central outer casing axis 114extends centrally through the casing 33 at a location centrally disposedwith respect to the outer casing surface 110. For instance, the centralouter casing axis 114 can extend centrally through the casing 33 at alocation centrally disposed with respect to the outer casing surface 110at the medial casing side 70 and at the lateral casing side 72 of thecasing 33. That is, the central outer casing axis 114 extends throughthe casing 33 at a location centrally disposed with respect to the outercasing surface 110 along a neck angle view. In one example, the neckangle view can be a sectional side elevation view of the casing 33 thatincludes the medial casing side 70 and the lateral casing side 72, andthe proximal and distal ends of the casing 33. Thus, the central outercasing axis 114 can be centrally disposed with respect to the outercasing surface 110 at anterior casing side 71 and at the posteriorcasing side 73. Thus, it can be said that the outer casing surface 110at the medial casing side 70 and at the lateral casing side 72 can atleast partially define the central outer casing axis 114. When implantedin a patient's femur, the central outer casing axis 114 is positioned inthe coronal plane of the patient's femur. As described in more detailbelow, the outer casing surface 110 at the anterior casing side 71 andthe posterior casing side 73 can also at least partially define thecentral outer casing axis 114.

The selectable neck angle 162 can be defined by the central neck axis 29and the central outer casing axis 114. The central neck axis 29 can becoplanar with the central outer casing axis 114 such that the axes 29and 114 intersect each other so as to define the selectable neck angle162. Alternatively, the central neck axis 29 and the central outercasing axis 114 can be non-coplanar with each other. For example, thecentral neck axis 29 may extend anteriorly out of plane with the centralouter casing axis 114 to position the femoral head anteriorly relativeto the outer casing and hence the coronal plane of the patient's femur.In another example, the central neck axis 29 may positioned in a planeoffset from, but extending parallel to, the plane of the central outercasing axis 114 (e.g., the coronal plane of the patient's femur when thefemoral stem is implanted in the patient's body).

It should be appreciated that the axes 29 and 114 intersect each otherwith respect to the neck angle view. In some examples, the neck angleview can be a side elevation view of the stem component 16 that includesthe distal end 19 of the stem component 16, the proximal end 17 of thestem component 16, the medial side 42 of the stem component 16, and thelateral side 44 of the stem component 16. In one example, the selectableneck angle 162 can be selected by determining an orientation of the core31 with respect to the casing 33 about an axis that is orientedsubstantially along the anterior-posterior direction. It is furtherappreciated that axes 29 and 114 intersect each other inside an outerperimeter of the core body 34 with respect to the side elevation neckangle view of the stem component that includes the proximal core bodyend 35, the distal core body end 37, the medial core body side 54, andthe lateral core body side 56. The outer perimeter of the core body 34is defined by the proximal core body end 35, the distal core body end37, the medial core body side 54, and the lateral core body side 56.

The femoral prosthesis 10 can be customized such that the neck 28 candefine any suitable selectable neck angle 162 as desired to position theprosthetic femoral head at a predetermined position relative to thelongitudinal axis of the outer casing and/or the coronal plane of thepatient's femur. In particular, the casing 33 can be fabricated suchthat the core 31 defines any suitable predetermined selectable neckangle 162. For instance, as illustrated in FIG. 7A, the core body 34 candefine a first selectable neck angle 162 a within the casing 33. Asillustrated in FIG. 7B, the core body 34 can define a second selectableneck angle 162 b within the casing 33 that is different than the firstselectable neck angle 162 a. As illustrated in FIG. 7C, the core body 34can be substantially centrally disposed within the casing 33, anddefines an associated third selectable neck angle. The core body 34 candefine any suitable number of selectable neck angles 162 that aredifferent than each of the first and second selectable neck angles 162.The selectable neck angles 162 defined by the core body 34 within thecasing 33 can be defined with respect to a neck angle view that isdefined by a sectional side elevation view that extends through both thecore body 34 and the casing 33 and includes the medial core body side 54and the lateral core body side 56, and the proximal and distal ends ofthe core body 34. The sectional side elevation view can further includethe medial casing side 70 and the lateral casing side 72.

In some examples, a permissible range of selectable neck angles 162 canbe determined such that the at least a portion of the core body 34 isencapsulated by the casing at all of the selectable neck angles 162within the permissible range of selectable neck angles 162. In oneexample, the permissible range of selectable neck angles 162 can be asubstantially 30 degree range. That is, the central neck axis 29 can beangularly offset from the central outer casing axis from a positionsubstantially 15 degrees offset from the central outer casing axis 114in a respective negative direction to a position substantially 15degrees offset from the central outer casing axis 114 in a respectivepositive direction that is opposite the respective negative direction.In this regard, it should be appreciated that the core body 34 can besized substantially smaller than the footprint defined by the outercasing surface 110 along the medial-lateral direction to achieve abroader range of selectable neck angles 162. As the size of the corebody 34 in the casing is increased with respect to the outer casingsurface 110 along the medial-lateral direction, the range of selectableneck angles 162 can decrease.

It should be further appreciated that the selectable neck angle 162 inthe range of selectable neck angles 162 can define a respectivemedial-lateral thickness profile of the casing 33. In particular, thecasing 33 can define a thickness 113 along the length of the core body34 that is a function of the selectable neck angle 162 relative to thecasing 33. The thickness 113 of the casing 33 can extend from the innercasing surface 108 to the outer casing surface 110 along themedial-lateral direction. As described above, the outer casing surface110 can define at least a portion of the outer surface of the femoralprosthesis 10. Further, the outer casing surface 110 can be nonparallelwith respect to the inner casing surface 108. It should be appreciatedthat as the orientation of the core body 34 varies to correspondinglyvary the selectable neck angle 162, the thickness of the casing 33 cansimilarly vary along the length of the casing 33. Further, the thickness113 of the casing 33 can be maintained above a minimum thickness alongan entirety of the medial and lateral casing sides 70 and 72,respectively. Alternatively, portions of the core body 34 can protrudethrough the casing 33, and in particular through the medial and lateralcasing sides 70 and 72. Accordingly, the outer casing surface 110 can beinterrupted by core body 34, and thus can be discontinuous in someembodiments.

As illustrated in FIG. 7A, the casing 33 can be fabricated such that thecentral core body axis 39 is angularly offset from to the central outercasing axis 114 with respect to the neck angle view. Thus, the centralcore body axis 39 can intersect the central outer casing axis 114 in thecore body 34 with respect to the neck angle view. Because the neck 28extends out from the core body 34 at the fixed neck angle 40, theangular offset of the central core body axis 39 can further define afirst selectable neck angle 162 a. In one example, the central core bodyaxis 39 can define a first angular offset with respect to the centralouter casing axis 114. In particular, the central core body axis 39 canextend medially with respect to the central outer casing axis 114 as itextends in the distal direction. The first angular offset can bereferred to as a negative angular offset in a negative direction.Further, the central inner casing axis 112 can be similarly angularlyoffset with respect to the central core body axis 39. For instance, thecentral inner casing axis 112 can define the first angular offset withrespect to the central outer casing axis 114.

As used herein, the term “angular offset” and derivatives thereof refersto a design in which two different axes are intended to be angularlyoffset, and thus outside of manufacturing tolerances. Thus, the term“angular offset” and derivatives thereof connotes that the angularoffset is greater than an angular offset of two axes that are designedto be coincident with each other but might be offset due tomanufacturing tolerances. In one example, the term “angular offset” caninclude an offset of at least approximately 1 degree, such as at leastapproximately 2 degrees.

Further, with continuing reference to FIG. 7A, the thickness 113 of thecasing at the medial casing side 70 can decrease as the casing 33extends in the distal direction. The thickness 113 of the casing at thelateral casing side 72 can increase as the casing extends in the distaldirection. The terms “increase” and “decrease” and derivatives thereofwhen used in connection with dimensions or measurements connotes thatthe distance or measurement increases or decreases, respectively, anamount greater than manufacturing tolerances of a distance ormeasurement that is designed to be constant.

As illustrated in FIG. 7B, the core body 34 can be oriented such thatthe central core body axis 39 is angularly offset from the central outercasing axis 114 with respect to the neck angle view so as to define asecond angular offset that is different than the first angular offset.Thus, FIG. 7B illustrates a second selectable neck angle 162 b that isdifferent than the first selectable neck angle 162 a of FIG. 7A. Thecentral core body axis 39 can intersect the central outer casing axis114 in the core body 34 so as to define the second selectable neck angle162 b. In one example, the second angular offset can be opposite thefirst angular offset. In particular, the central core body axis 39 canextend laterally with respect to the central outer casing axis 114 as itextends in the distal direction so as to define the second angularoffset. The second angular offset can be referred to as a positiveangular offset in a positive direction. Further, the central innercasing axis 112 can be similarly angularly offset with respect to thecentral core body axis 39. For instance, the central inner casing axis112 can define the second angular offset with respect to the centralouter casing axis 114. Further, the thickness 113 of the medial casingside 70 can increase as the casing 33 extends in the distal direction.The thickness 113 of the lateral casing side 72 can decrease as thecasing extends in the distal direction. The core body 34 of the femoralprosthesis illustrated in FIG. 7B can be substantially identical to thecore body 34 of the femoral prosthesis illustrated in FIG. 7A

Accordingly, it should be appreciated that a plurality of differentfemoral prostheses 10 can be manufactured having different selectableneck angles. For instance, the respective core bodies 34 of each of theplurality of cores 31 having substantially the same fixed neck angle canbe encased by respective casings 33 that are fabricated about theirrespective outer core body surfaces 109, such that when the casings 33are inserted into the medullary canal of a femoral bone at substantiallythe same relative orientation with respect to the bone, the respectivenecks having the same fixed neck angle will extend medially andsuperiorly at different angles with respect to the central axis of thefemur. In one example, the casings 33 can have substantially identicallysized and shaped outer casing surfaces 110.

The relative orientations of the central core body axis 39, the centralinner casing axis 112, and the central outer casing axis 114 describedabove can be determined with respect to a sectional side elevation viewof the stem component 16 that includes the medial casing side 70 and thelateral casing side 72. Further, an angle defined by the central outercasing axis 114 and either or both of the central core body axis 39 andthe central inner casing axis 112 can be curved where they intersectwhen viewed along the sectional side elevation view. Thus, the angle canbe measured by respective tangents of one or more up to all of thecentral outer casing axis 114 and either or both of the central corebony axis 39 and the central inner casing axis 112, when curved, wherethey intersect. It is further recognized that the central core body axis39 can be angularly offset with respect to the central inner casing axis112. For instance, it is recognized that portions of the inner casingsurface 108 can be spaced from the outer core body surface 109, such aswhen the casing 33 is additively manufactured as a separate component 61as shown in FIG. 3 .

As illustrated in FIG. 7C, the core body 34 defines a third selectableneck angle 162 c that is different than each of the first and secondselectable neck angles 162 a and 162 b. In particular, the core body 34can be oriented with respect to the casing 33 such that the central corebody axis 39 is oriented parallel with the central outer casing axis 114with respect to the neck angle view. Thus, the core body 34 can be saidto be centrally disposed in the casing 33 with respect to the neck angleview. In some examples, the central core body axis 39 can be coincidentwith the central outer casing axis 114 with respect to the neck angleview. Further, the central inner casing axis 112 can be parallel to orcoincident with the central core body axis 39 with respect to the neckangle view. Further, the thickness 113 of the medial casing side 70 ofthe casing 33 can be substantially constant along an entirety of thelength of the core body 34. Thus, the third selectable neck angle 162 ccan be equal to the fixed neck angle 40. Similarly, the thickness 113 ofthe lateral casing side 72 can be substantially constant along anentirety of the length of the core body 34. In one example, thethickness of the casing 33 at the medial casing side 70 is greater thanthe thickness of the casing 33 at the lateral casing side 72. In otherexamples, the thickness of the casing 33 at the medial casing side 70 isless than the thickness of the casing 33 at the lateral casing side 72.As described above, the inner core 31 of the femoral prosthesisillustrated in FIG. 7C can be substantially identical to the inner core31 of the femoral prosthesis illustrated in each of FIG. 7A and FIG. 7B.That is, the inner core shown in FIGS. 7A-7C can have the substantiallysame size and shape.

With continuing reference to FIGS. 7A-7C, it should be appreciated amethod can be provided for fabricating the femoral prostheses 10 thateach includes the core body 34 that is configured to be inserted intothe medullary canal 21 of the femur 23. The femoral prostheses 10 caninclude substantially equally sized and shaped core bodies 34 havingdifferent orientations in the respective casings 33. A method offabricating the femoral prosthesis 10 can include the step of applyingthe porous casing 33 onto the core body 34 so as to define the innercasing surface 108 that faces the core body 34 and the outer casingsurface 110 opposite the inner casing surface 108, such that the centralcore body axis 39 of the core body 34 is angularly offset with respectto the central outer casing axis 114 defined by the outer casing surface110. The angular offset between the central core body axis 39 and thecentral outer casing axis 114 similarly determines the selectable neckangle 162.

For instance, the first femoral prosthesis can include a first core bodyand a first neck that extends out with respect to the first core body atthe fixed neck angle 40 and at a first selectable neck angle 162 a. Thesecond femoral prosthesis can include includes a second core body and asecond neck that extends out with respect to the second core body at thefixed neck angle 40 and at a second selectable neck angle 162 bdifferent than the first selectable neck angle 162 a.

The method can include the step of manufacturing a first porous casing33 onto a first core body 34 so as to define a first femoral prosthesis10 whereby 1) a first neck 28 extends out with respect to the proximalend of the first core body 34 at a fixed neck angle 40, and 2) the firstporous casing 33 defines a first inner casing surface 108 that faces thefirst core body 34 and a first outer casing surface 110 opposite thefirst inner casing surface 108, wherein the first outer casing 33extends along a first central outer casing axis 114, and the first neck28 extends from the first core body 34 at a first selectable neck angle162 a with respect to the first central outer casing axis 114.

The method can include the step of manufacturing a second porous casing33 onto a second core body 34 so as to define a second femoralprosthesis 10 whereby 1) a second neck 28 extends out with respect tothe proximal end of the second core body 34 at the fixed neck angle 40,and 2) the second porous casing 33 defines a second inner casing surface108 that faces the second core body 34 and a second outer casing surface110 opposite the second inner casing surface 108, wherein the secondouter casing 33 extends along a second central outer casing axis 114,and the second neck 28 extends from the second core body 34 at a secondselectable neck angle 162 b with respect to the second central outercasing axis 114 that is different than the first selectable neck angle162 a.

Referring now to FIGS. 8A-8C, and as described above, the core body 34and thus the inner core 31 of the femoral prosthesis, 10 can be tiltedalong the anterior-posterior direction with respect to the casing 33. Asdescribed above, the central outer casing axis 114 extends centrallythrough the casing 33 at a location centrally disposed with respect tothe outer casing surface 110. For instance, the central outer casingaxis 114 can extend centrally through the casing 33 at a locationcentrally disposed with respect to the outer casing surface 110 at theanterior casing side 71 and at the posterior casing side 73 of thecasing 33. That is, the central outer casing axis 114 extends throughthe casing 33 at a location centrally disposed with respect to the outercasing surface 110 along a tilt angle view. The tilt angle view can bedefined by a sectional side elevation view of the casing 33 thatincludes the anterior casing side 71, the posterior casing side 73, andthe proximal and distal ends of the casing 33. Thus, the central outercasing axis 114 can be centrally disposed with respect to the outercasing surface 110 at the anterior casing side 71 and at the posteriorcasing side 73. Accordingly, it can be said that the outer casingsurface 110 at the anterior casing side 71 and at the posterior casingside 73 can at least partially define the central outer casing axis 114.As described above, the outer casing surface 110 at the medial andlateral casing sides can also at least partially define the centralouter casing axis 114.

The tilt angle 165 can be defined by the central core body axis 39 andthe central outer casing axis 114. The central core body axis 39 can becoplanar with the central outer casing axis 114 such that the axes 39and 114 intersect each other so as to define the tilt angle 165.Alternatively, the central core body axis 39 and the central outercasing axis 114 can be non-coplanar with each other. Either way, theaxes 39 and 114 intersect each other with respect to the tilt angleview. In some examples, the tilt angle view can be a side elevation viewof the stem component 16 that includes the distal end 19 of the stemcomponent 16, the proximal end 17 of the stem component 16, the anteriorside 46 of the stem component 16 and the posterior side 48 of the stemcomponent 16. In one example, the tilt angle 165 can be selected bydetermining an orientation of the core 31 with respect to the casing 33about an axis that is oriented substantially along theanterior-posterior direction. It is further appreciated that axes 39 and114 intersect each other inside a respective outer perimeter of the corebody 34 with respect to the side elevation tilt angle view of the stemcomponent that includes the proximal core body end 35, the distal corebody end 37, the anterior core body side 57 and the posterior core bodyside 59. The respective outer perimeter of the core body 34 is definedby the proximal core body end 35, the distal core body end 37, theanterior core body side 57, and the posterior core body side 59.

The femoral prosthesis 10 can be customized such that the core body 34and thus the inner core 31 can define any suitable tilt angle 165 asdesired. In particular, the casing 33 can be fabricated such that thecore 31 defines any suitable tilt angle 165 as desired. For instance, asillustrated in FIG. 8A, the core body 34 can define a first tilt angle165 a within the casing 33. As illustrated in FIG. 8B, the core body 34can define a second tilt angle 165 b within the casing 33 that isdifferent than the first tilt angle 165 a. As illustrated in FIG. 8C,the core body 34 can be in a neutral tilt position whereby the core bodyis substantially centrally disposed within the casing 33 with respect tothe tilt angle view. The core body 34 of FIG. 8C can be substantiallyidentical to the core body 34 of FIGS. 8A and 8B. The tilt angles 165defined by the core body 34 within the casing 33 can be defined withrespect to a respective sectional side elevation tilt angle view thatextends through both the core body 34 and the casing 33 and includes theanterior core body side 57 and the posterior core body side 59. Thesectional side elevation tilt angle view can further include theanterior casing side 71 and the posterior casing side 73.

In some examples, a permissible range of tilt angles 165 can bedetermined such that the at least a portion of the core body 34 isencapsulated by the casing at all of the tilt angles 165 within thepermissible range of tilt angles 165. In one example, the permissiblerange of tilt angles 165 can be a substantially 30 degree range. Thatis, the central core body axis 39 can be angularly offset from thecentral outer casing axis 114 from a position substantially 15 degreesoffset from the central outer casing axis 114 in a respective positivedirection to a position substantially 15 degrees offset from the centralouter casing axis 114 in a respective negative direction that isopposite the respective positive direction. In this regard, it should beappreciated that the core body 34 can be sized substantially smallerthan the footprint defined by the outer casing surface 110 along theanterior-posterior direction to achieve a broader range of tilt angles165. As the size of the core body 34 in the casing is increased withrespect to the outer casing surface 110 along the anterior-posteriordirection, the range of tilt angles 165 can decrease.

It should be further appreciated that the tilt angle 165 in the range oftilt angles 165 can define a respective anterior-posterior thicknessprofile of the casing 33. In particular, the casing 33 can define athickness 119 along the length of the core body 34 that is a function ofthe tilt angle 165 relative to the casing 33. The thickness 119 of thecasing 33 can extend from the inner casing surface 108 to the outercasing surface 110 along the anterior-posterior direction. As describedabove, the outer casing surface 110 can define at least a portion of theouter surface of the femoral prosthesis 10. Further, the outer casingsurface 110 can be nonparallel with respect to the inner casing surface108. It should be appreciated that as the orientation of the core body34 varies to correspondingly vary the tilt angle 165, the thickness ofthe casing 33 can similarly vary along the length of the casing 33.Further, the thickness 119 of the casing 33 can be maintained above aminimum thickness along an entirety of the anterior and posterior casingsides 71 and 73, respectively. Alternatively, portions of the core body34 can protrude through the casing 33, and in particular through theanterior and posterior casing sides 71 and 73. Accordingly, the outercasing surface 110 can be interrupted by core body 34, and thus can bediscontinuous in some embodiments.

As illustrated in FIG. 8A, the casing 33 can be fabricated such that thecentral core body axis 39 is angularly offset from to the central outercasing axis 114 with respect to the tilt angle view. Thus, the centralcore body axis 39 can intersect the central outer casing axis 114 in thecore body 34 with respect to the tilt angle view. The central core bodyaxis 39 and the central outer casing axis 114 can define a first tiltangle 165 a with respect to the tilt angle view. In one example, thecentral core body axis 39 can define a first angular tilt offset withrespect to the central outer casing axis 114 in the tilt angle view. Inparticular, the central core body axis 39 can extend anteriorly withrespect to the central outer casing axis 114 as it extends in the distaldirection. The first angular tilt offset can be referred to as anegative angular tilt offset in a negative tilt direction. Further, asthe central inner casing axis 112 can be coincident with the centralcore body axis 39, the central inner casing axis 112 can be similarlyangularly offset with respect to the central outer casing axis 114.Thus, the central inner casing axis 112 can define the first tilt angle165 a with respect to the central outer casing axis 114.

As used herein, the term “angular tilt offset” and derivatives thereofrefers to a design in which two different axes are intended to beangularly offset with respect to the tilt angle view, and thus outsideof manufacturing tolerances. Thus, the term “angular tilt offset” andderivatives thereof connotes that the angular tilt offset is greaterthan an angular tilt offset of two axes that are designed to becoincident with each other but might be offset with respect to the tiltangle view due to manufacturing tolerances. In one example, the term“angular tilt offset” can include an offset of at least approximately 1degree, such as at least approximately 2 degrees.

Further, with continuing reference to FIG. 8A, the thickness 119 of thecasing at the anterior casing side 71 can decrease as the casing 33extends in the distal direction. The thickness 119 of the casing at theposterior casing side 73 can increase as the casing extends in thedistal direction. The terms “increase” and “decrease” and derivativesthereof when used in connection with dimensions or measurements connotesthat the distance or measurement increases or decreases, respectively,an amount greater than manufacturing tolerances of a distance ormeasurement that is designed to be constant.

As illustrated in FIG. 8B, the core body 34 can be oriented such thatthe central core body axis 39 is angularly offset from the central outercasing axis 114 with respect to the tilt angle view so as to define asecond tilt angle 165 b that is different than the first tilt angle 165a. The central core body axis 39 can intersect the central outer casingaxis 114 in the core body 34 with respect to the tilt angle view so asto define the second tilt angle 165 b. In one example, the second tiltangle 165 b can be opposite the first tilt angle 165 a. In particular,the central core body axis 39 can extend posteriorly with respect to thecentral outer casing axis 114 as it extends in the distal direction soas to define the second tilt angle 165 b. The second tilt angle 165 bcan be referred to as a positive tilt angle in a positive direction.Further, as the central inner casing axis 112 can be coincident with thecentral core body axis 39, the central inner casing axis 112 can besimilarly angularly offset with respect to the central core body axis39. For instance, the central inner casing axis 112 can define thesecond tilt angle 165 b with respect to the central outer casing axis114. Further, the thickness 119 of the anterior casing side 71 canincrease as the casing 33 extends in the distal direction. The thickness119 of the posterior casing side 73 can decrease as the casing extendsin the distal direction. As described above, the inner core 31 of thefemoral prosthesis illustrated in FIG. 8B can be substantially identicalto the inner core 31 of the femoral prosthesis illustrated in FIG. 8A.

Accordingly, it should be appreciated that a plurality of differentfemoral prostheses 10 can be manufactured having different tilt angles.For instance, the respective core bodies 34 of each of the plurality ofcores 31 can have substantially the same size and shape, but can definedifferent tilt angles with respect to the respective outer casings 33.Further, the respective outer casings 33 can have substantiallyidentically sized and shaped outer casing surfaces 110.

The relative orientations of the central core body axis 39, the centralinner casing axis 112, and the central outer casing axis 114 describedabove with respect to the tilt angle can be determined in the sectionalside elevation tilt angle view of the stem component 16 that includesthe anterior casing side 71 and the posterior casing side 73, and theproximal and distal ends of the casing 33. Further, the tilt angledefined by the central outer casing axis 114 and either or both of thecentral core body axis 39 and the central inner casing axis 112 can becurved where they intersect when viewed along the tilt angle view. Thus,the angle can be measured by respective tangents of one or more up toall of the central outer casing axis 114 and either or both of thecentral core body axis 39 and the central inner casing axis 112, whencurved, where they intersect. It is further recognized that the centralcore body axis 39 can be angularly offset with respect to the centralinner casing axis 112. For instance, it is recognized that portions ofthe inner casing surface 108 can be spaced from the outer core bodysurface 109, such as when the casing 33 is additively manufactured as aseparate component 61 as shown in FIG. 3 .

As illustrated in FIG. 8C, the core body 34 can define a neutral tiltposition in the casing 33. In particular, the core body 34 can beoriented with respect to the casing 33 such that the central core bodyaxis 39 is oriented substantially parallel with the central outer casingaxis 114 along the sectional side elevation tilt angle view. In someexamples, the central core body axis 39 can be substantially coincidentwith the central outer casing axis 114. Further, the central innercasing axis 112 can be parallel to or coincident with the central corebody axis 39. Further still, the thickness 119 of the anterior casingside 71 of the casing 33 can be substantially constant along an entiretyof the length of the core body 34. Similarly, the thickness 119 of theposterior casing side 73 can be substantially constant along an entiretyof the length of the core body 34. In one example, the thickness of thecasing 33 at the anterior casing side 71 is greater than the thicknessof the casing 33 at the posterior casing side 73. In other examples, thethickness of the casing 33 at the anterior casing side 71 is less thanthe thickness of the casing 33 at the posterior casing side 73. The corebody 34 of the femoral prosthesis illustrated in FIG. 8C can besubstantially identical to the core body 34 of the femoral prosthesisillustrated in FIGS. 8A and 8B.

With continuing reference to FIGS. 8A-8C, it should be appreciated amethod can be provided for fabricating the femoral prostheses 10 thateach includes the core body 34 that is configured to be inserted intothe medullary canal 21 of the femur 23. The femoral prostheses 10 caninclude substantially identically sized and shaped core bodies 34 havingdifferent tilt angles in the respective casings 33. A method offabricating the femoral prosthesis 10 can include the step of applyingthe porous casing 33 onto the core body 34 so as to define the innercasing surface 108 that faces the core body 34 and the outer casingsurface 110 opposite the inner casing surface 108, such that the centralcore body axis 39 of the core body 34 is angularly offset with respectto the central outer casing axis 114 defined by the outer casing surface110 with respect to the tilt angle view. The angular offset between thecentral core body axis 39 and the central outer casing axis 114similarly determines the tilt angle 165.

For instance, the first femoral prosthesis can include a first core body34 having a first core body axis 39 that has a first orientation in therespective first porous casing 33 with respect to the tilt angle view,and a femoral prosthesis that includes a second core body 34 having asecond core body axis 39 that has a second orientation in the respectivesecond porous casing 33 with respect to the tilt angle view. The secondorientation is different than the first orientation with respect to therespective casing 33. Thus, the first femoral prosthesis defines thefirst tilt angle, and the second femoral prosthesis defines the secondtilt angle that is different than the first tilt angle.

The method can include the step of manufacturing the first porous casing33 onto the first core body 34 so as to define the first femoralprosthesis 10 whereby the first core body axis 39 defines the first tiltangle 165 a with respect to the outer central casing axis 114. Themethod can include the step of manufacturing the second porous casing 33onto the second core body 34 so as to define the second femoralprosthesis 10 whereby the second core body axis 39 defines the secondtilt angle with respect to the outer central casing axis 114.

Referring now to FIGS. 9A-9C, and as described above, the femoralprosthesis 10 can include the rotational position 166 with respect tothe casing 33. Thus, the neck 28 can extend out from the core body 34 atthe fixed neck angle 40 and at the rotational position 166 with respectto the outer casing surface 110. Further, because the inner casingsurface 108 can extend along the outer core body surface 109, thecentral neck axis of the neck 28 can extend out from the central innercasing axis 112 at the fixed neck angle 40 (see FIGS. 1-2B). As will nowbe described, the outer casing 33 can define the rotational position166. For instance, the outer casing 33 can be fabricated such that thecore 31, and thus the neck 28, can define any suitable orientation withrespect to the outer casing 33 about the axis of rotation 167. The axisof rotation 167 can be defined by the central core body axis 39, or canbe offset from the central core body axis 39. As the inner core 31defines the rotational position 166 is adjusted in a range ofpermissible rotational positions 166, the neck 28 defines a position ina range of permissible selective positions that revolve about the axisof rotation 167.

The femoral prosthesis 10 can be customized such that the core body 34,and thus the core 31, can define any suitable rotational position 166with respect to the axis of rotation 167. In particular, the casing 33can be fabricated such that the core body 34 defines any suitablepredetermined rotational position 166 with respect to the outer casingsurface 110.

For instance, as illustrated in FIG. 9A, the core body 34 can define afirst rotational position 166 a within the casing 33. Thus, the core 31,including the neck 28, can similarly define the first rotationalposition 166 a. As illustrated in FIG. 9B, the core body 34 can define asecond rotational position 166 within the casing 33 that is differentthan the first orientation. Thus, the core 31, including the neck 28,can similarly define the second rotational position 166. As illustratedin FIG. 9C, the core body 34 can define a third rotational position 166c within the casing 33 that is different than each of the first andsecond rotational positions 166 a and 166 b, respectively. Inparticular, the core body 34 can be centrally disposed within the casing33 so as to define the third rotational position 166 c. The core 31,including the neck 28, can similarly define the first, second, and thirdrotational positions. The rotational positions 166 of the core body 34within the casing 33 can be defined with respect to a rotational view.The rotational view can be a sectional plan view that extends throughboth the core body 34 and the casing 33 and includes the anterior casingside 71, the posterior casing side 73, the medial casing side 70, andthe lateral casing side 72. The sectional plan view can be along a planethat is substantially perpendicular with respect to the central corebody axis.

In some examples, the range of rotational positions 166 can bedetermined such that the at least a portion of the core body 34 isencapsulated by the casing 33 at all of the rotational positions 166within the range of permissible rotational positions 166. The range ofpermissible rotational positions 166 can be determined such that thecore body 34 does not protrude through the outer casing surface 110 atany of the rotational positions 166 in the range of permissiblerotational positions 166. Further, the range of permissible rotationalpositions 166 can be determined such that a thickness 115 of the casing33 at the anterior and posterior casing sides 71 and 73, respectively,can be maintained above a minimum thickness along an entirety of theanterior and posterior casing sides 71 and 73, respectively.

Referring now to FIGS. 9A-9B in particular, the range of rotationalpositions 166 can be defined by an angle of rotation 168. The angle ofrotation 168 can be defined by a central core body axis 169 and acentral fixed casing axis 171. The core body axis 169 can extend fromthe medial core body side 54 and the lateral core body side 56. Further,the core body axis 169 can bisect each of the medial core body side 54and the lateral core body side 56. These sides can be referred to as themedial core body side 54 and the lateral core body side 56 even whenangulated about the axis of rotation 167, as they define the medial andlateral extent of the core body 34 when the core body 34 is in a neutralnon-angulated position. It is recognized that the core body axis 169 hasan orientation that varies depending on the rotational position 166 ofthe core body 34. The fixed casing axis 171 can extend from the outercasing surface 110 at the medial casing side 70 to the outer casingsurface 110 at the lateral casing side 72. For instance, the fixedcasing axis 171 can bisect the outer casing surface 110 at the medialcasing side 70 and the outer casing surface 110 at the lateral casingside 72. In one example, the angle of rotation 168 can be at leastapproximately 5 degrees up to at least approximately 15 degrees.

The range of rotational positions 166 as defined by the angle ofrotation 168 can be a substantially 30 degree range. That is, the angleof rotation 168 can range up to approximately 15 degrees clockwise andapproximately 15 degrees counterclockwise. For instance, the range ofrotational positions 166 as defined by the angle of rotation 168 can bea substantially 20 degree range. That is, the angle of rotation 168 canrange up to approximately 10 degrees clockwise and approximately 10degrees counterclockwise. In some examples, the range of rotationalpositions 166 as defined by the angle of rotation 168 can be asubstantially 20 degree range. That is, the angle of rotation 168 canrange up to approximately 10 degrees clockwise and approximately 10degrees counterclockwise. In other examples, the range of rotationalpositions 166 as defined by the angle of rotation 168 can be asubstantially 10 degree range. That is, the angle of rotation 168 canrange up to approximately 5 degrees clockwise and approximately 5degrees counterclockwise. In still other examples, the range ofrotational positions 166 as defined by the angle of rotation 168 can bea substantially 5 degree range. That is, the angle of rotation 168 canrange up to approximately 2.5 degrees clockwise and approximately 2.5degrees counterclockwise.

In this regard, it should be appreciated that the core body 34 can besized substantially smaller than the footprint defined by the outercasing surface 110 to achieve a broader range of rotational positions166. As the size of the core body 34 in the casing is increased withrespect to the outer casing surface 110, the range of rotationalpositions 166 can decrease.

As illustrated in FIG. 9A, a first negative angle of rotation 168 a canbe counterclockwise, such that the core body 34 defines a negative firstrotational position 166 a. The first rotational position 166 a in therange of rotational positions 166 can define a respective firstanterior-posterior thickness profile of the casing 33. In particular,the casing 33 can define a thickness 115 along the length of the corebody 34 that is a function of the rotational position 166 of the corebody 34 relative to the casing 33. The thickness 115 of the casing 33can extend from the inner casing surface 108 to the outer casing surface110 at the anterior casing side 71 and the posterior casing side 73. Asdescribed above, the outer casing surface 110 can define at least aportion of the outer surface of the femoral prosthesis 10.

As the rotational position 166 of the core body 34 varies, the thickness115 of the anterior casing side 71 and the posterior casing side 71 canvary. When the core body 34 is in the first rotational position 166 aillustrated in FIG. 9A, the thickness 115 of the casing 33 at theanterior casing side 71 can increase as the anterior casing side 71extends in the medial direction from the lateral casing side 72 towardthe medial casing side 70. Thus, the medial core body side 54 can bespaced a first distance from the outer casing surface 110 at theanterior casing side 71 along the anterior-posterior direction. Inparticular, the anterior side of the medial core body side 54 can bespaced the first distance from the outer casing surface 110 at theanterior casing side 71 along the anterior-posterior direction. Thelateral core body side 56 can be spaced a second distance from the outercasing surface 110 at the anterior casing side 71 along theanterior-posterior direction. In particular, the anterior side of thelateral core body side 56 can be spaced the second distance from theouter casing surface 110 at the anterior casing side 71 along theanterior-posterior direction. The first distance can be different thanthe second distance when the core body 34 is angulated about the axis ofrotation 167. In one example, for instance when the core body 34 isangulated to define the negative angle of rotation 168 a, the seconddistance can be less than the first distance. Alternatively, thethickness 115 of the casing 33 at the anterior casing side 71 candecrease less than it decreases when the core body 34 is in the secondrotational position 166 b described with respect to FIG. 9B.

Conversely, the thickness 115 of the casing 33 at the posterior casingside 73 can decrease as the anterior casing side 71 extends in themedial direction. Thus, the medial core body side 54 can be spaced athird distance from the outer casing surface 110 at the posterior casingside 73 along the anterior-posterior direction. In particular, theposterior side of the medial core body side 54 can be spaced the thirddistance from the outer casing surface 110 at the posterior casing side73 along the anterior-posterior direction. The lateral core body side 56can be spaced a fourth distance from the outer casing surface 110 at theposterior casing side 73 along the anterior-posterior direction. Inparticular, the posterior side of the lateral core body side 56 can bespaced the fourth distance from the outer casing surface 110 at theposterior casing side 73 along the anterior-posterior direction. Thethird distance can be different than the fourth distance when the corebody 34 is angulated about the axis of rotation 167. In one example, forinstance when the core body 34 is angulated to define the first negativeangle of rotation 168 a, the third distance can be less than the fourthdistance. Further, the third distance can be substantially equal to thefirst distance, and the fourth distance can be substantially equal tothe second distance. Alternatively, depending on the dimensions of thecore body 34, the position of the core body 34 with respect to theanterior and posterior casing sides 71 and 73, respectively, and thelocation of the axis of rotation 167, the third distance can bedifferent than the first distance, and the fourth distance can bedifferent than the second distance. The first distance, the seconddistance, the third distance, and the fourth distance can be measured ina plane that is oriented substantially perpendicular to the central corebody axis 39. The plane can bisect the core body 34 in some examples.

Referring now to FIG. 9B, a second positive angle of rotation 168 b canbe clockwise, and thus opposite the first negative angle of rotation 168a described above with respect to FIG. 9A. Thus, the core body 34defines a positive second rotational position 166 b. The secondrotational position 166 b in the range of rotational positions 166 candefine a respective second anterior-posterior thickness profile of thecasing 33. In particular, when the core body 34 is in the secondrotational position 166 illustrated in FIG. 9B, the thickness 115 of thecasing 33 at the anterior casing side 71 can decrease as the anteriorcasing side 71 extends in the medial direction. Thus, the medial corebody side 54 can be spaced a first distance from the outer casingsurface 110 at the anterior casing side 71 along the anterior-posteriordirection. The lateral core body side 56 can be spaced a second distancefrom the outer casing surface 110 at the anterior casing side 71 alongthe anterior-posterior direction. The first distance can be differentthan the second distance when the core body 34 is angulated about theaxis of rotation 167. In one example, for instance when the core body 34is angulated to define the positive angle of rotation 168 b, the firstdistance can be less than the second distance. direction

Conversely, the thickness 115 of the casing 33 at the posterior casingside 73 can increase as the anterior casing side 71 extends in themedial direction. Thus, the medial core body side 54 can be spaced athird distance from the outer casing surface 110 at the posterior casingside 73 along the anterior-posterior direction. The lateral core bodyside 56 can be spaced a fourth distance from the outer casing surface110 at the posterior casing side 73 along the anterior-posteriordirection. The third distance can be different than the fourth distancewhen the core body 34 is angulated about the axis of rotation 167. Inone example, for instance when the core body 34 is angulated to definethe second positive angle of rotation 168 b, the third distance can begreater than the fourth distance. Further, the third distance can besubstantially equal to the first distance, and the fourth distance canbe substantially equal to the second distance. Alternatively, dependingon the dimensions of the core body 34, the position of the core body 34with respect to the anterior and posterior casing sides 71 and 73,respectively, and the location of the axis of rotation 167, the thirddistance can be different than the first distance, and the fourthdistance can be different than the second distance.

It should therefore be appreciated that when first and second femoralprostheses 10 define different first and second rotational positions 166a and 166 b, respectively, the core 31 of second femoral prosthesis 10is rotated about the axis of rotation 167 with respect to first femoralprosthesis 10. The central casing axis 171 can be referred to as a fixedcentral casing axis because the central casing axis 171 of the firstfemoral prosthesis 10 can have the same position and orientation as thecentral casing axis 171 of the second femoral prosthesis. Further, themedial core body side 54 of the first femoral prosthesis 10 can bespaced further from the anterior casing side 71 than the medial corebody side 54 of the second femoral prosthesis is spaced from theanterior casing side 71. The lateral core body side 56 of the secondfemoral prosthesis 10 can be spaced further from the anterior casingside 71 than the lateral core body side 56 of the first femoralprosthesis is spaced from the anterior casing side 71. The medial corebody side 54 of the second femoral prosthesis 10 can be spaced furtherfrom the posterior casing side 73 than the medial core body side 54 ofthe first femoral prosthesis is spaced from the posterior casing side73. The lateral core body side 56 of the first femoral prosthesis 10 canbe spaced further from the posterior casing side 73 than the lateralcore body side 56 of the second femoral prosthesis is spaced from theposterior casing side 73.

As illustrated in FIG. 9C, the core body 34 can be positioned in a thirdrotational position 166 c with respect to the casing 33. For instance,the third rotational position 166 c can define a neutral positionwhereby the core body axis 169 is substantially parallel to the fixedcasing axis 171. For instance, the core body axis 169 can besubstantially coincident with the fixed casing axis 171. Further, whenthe core body 34 is in the third rotational position, the thickness 115of the anterior casing side 71 can substantially constant along themedial-lateral direction from the medial core body side 54 to thelateral core body side, depending on the geometry of the core body 34and casing 33 with respect to the rotational view. Further, thethickness of the posterior casing side 73 can be substantially constantalong the medial-lateral direction from the medial core body side 54 tothe lateral core body side 56, depending on the geometry of the corebody 34 and casing 33 with respect to the rotational view. Further, themedial and lateral core body sides 54 and 56, respectively, can bealigned along the medial-lateral direction.

With continuing reference to FIGS. 9A-9C, it should be appreciated amethod can be provided for fabricating the femoral prostheses 10 thateach includes the core body 34 that is configured to be inserted intothe medullary canal 21 of the femur 23. The femoral prostheses 10 caninclude substantially equally sized and shaped core bodies 34 havingdifferent rotational position 166 in the respective casings 33. A methodof fabricating the femoral prosthesis 10 can include the step ofapplying the porous casing 33 onto the core body 34 so as to define theinner casing surface 108 that faces the core body 34 and the outercasing surface 110 opposite the inner casing surface 108, such that thecore body axis 169 defines a respective orientation with respect to thefixed casing axis 171. For instance, the core body axis 169 can beangularly offset with respect to the fixed casing axis 171 in a positivedirection, a negative direction, or the core body axis 169 can besubstantially coincident with the fixed casing axis 171.

The method can include the step of manufacturing a first porous casing33 onto a first core body 34 so as to define a first femoral prosthesis10 whereby 1) a first neck 28 extends out with respect to the proximalend of the first core body 34 at a fixed neck angle 40, and 2) the firstporous casing 33 defines a first inner casing surface 108 that faces thefirst core body 34 and a first outer casing surface 110 opposite thefirst inner casing surface 108. The core body axis 169 can define therespective orientation with respect to the fixed casing axis 171. Themethod can further include fabricating a first femoral component 10including the first porous casing and a first inner core 31 thatincludes the first core body 34 and the first neck 28.

The method can include the step of manufacturing a second porous casing33 onto a second core body 34 so as to define a first femoral prosthesis10 whereby 1) a second neck 28 extends out with respect to the proximalend of the second core body 34 at a fixed neck angle 40, and 2) thesecond porous casing 33 defines a second inner casing surface 108 thatfaces the second core body 34 and a second outer casing surface 110opposite the second inner casing surface 108. The core body axis 169 candefine the respective orientation with respect to the fixed casing axis171. The method can further include fabricating a first femoralcomponent 10 including the first porous casing and a first inner core 31that includes the first core body 34 and the first neck 28. The firstand second femoral prostheses can further define different selectableneck angles 162 described above.

Referring now to FIGS. 10A-10B in particular, and as described above,the femoral prosthesis, can include a neck offset 164. For instance, theneck offset 164 can thus extend from the outer casing surface 110 of theouter casing 33 to the neck 28 substantially along the central neck axis29. The neck offset 164 can be defined by a distance from the casing 33to the neck 28 substantially along the central neck axis 29. Inparticular, the neck offset 164 can be defined by a distance from aproximal end of the casing 33 to the neck 28 substantially along thecentral neck axis 29. As will now be described, a position of the corebody 34 in the casing 33 can determine the neck offset 164. Forinstance, the outer casing 33 can be fabricated such that the core body34 can define any suitable position in the outer casing 33 that, inturn, determines the neck offset 164.

As illustrated in FIG. 10A, a first neck offset 164 a from the neck 28to the casing 33 substantially along the central neck axis 29 can definea first distance. When the core 31 includes the shoulder 32, the firstdistance can be defined by a minimum first neck offset 164 a when theshoulder 32 abuts the casing 33. Thus, the first neck offset 164 a canbe defined as the dimension of the shoulder 32 substantially along thecentral neck axis 29. Alternatively, when the core 31 does not includethe shoulder 32, then the first neck offset 164 a can be defined by thedimension of the neck 28 along the central neck axis 29 when the neck 28abuts the casing 33. Thus, the first neck offset 164 a can beapproximately zero in one examples. Alternatively, the neck 28 can bespaced from the outer casing surface 110 along the central neck axis 29so as to define the first neck offset 164 a.

As illustrated in FIG. 10B, a second neck offset 164 b from the neck 28to the casing 33 substantially along the central neck axis 29 that isdifferent than the first neck offset 164 a of FIG. 10A. The second neckoffset 164 b can be greater than or less than the first neck offset 164a. In the example illustrated in FIG. 10B, the second neck offset 164 bis greater than the first neck offset 164 a. Further, because the neck28 is positioned increasingly superiorly and medially as the neck offset164 increases, the thickness 113 of the medial casing side 70 candecrease.

Thus, when a first femoral implant 10 or stem component 16 defines afirst neck offset 164 a, and a second femoral implant 10 or stemcomponent 16 defines a second neck offset 164 b that is different thanthe first neck offset 164 a, a first thickness 113 of the medial casingside 70 from the inner casing surface 108 to the outer casing surface110 is of the casing 33 of the first femoral implant 10 or stemcomponent 16 is different than a second thickness 113 of the medialcasing side 70 from the inner casing surface 108 to the outer casingsurface 110 is of the casing 33 of the second femoral implant 10 or stemcomponent 16. For instance, when the first neck offset 164 a is greaterthan the second neck offset 164 b, the first thickness 113 can begreater than the second thickness 113. Conversely, when the first neckoffset 164 a is less than the second neck offset 164 b, the firstthickness 113 can be less than the second thickness 113.

It should be appreciated that while the neck offset 164 can at leastpartially determine a position of the neck 28 with respect to the outercasing surface 110 substantially along the central neck axis 29, one orboth of the selectable neck angle 162 and the rotational position 166 ofthe core body 34, and thus of the core 31, can further determine theposition of the neck 28 and an orientation of the neck with respect tothe outer casing surface 110. Because the trunnion 30 extends from theneck 28 and is configured to be coupled to the head component 18, one ormore up to all of the neck offset 164, the selectable neck angle 162,and the rotational position 166 of the core body 34 can determine theposition and orientation of the head component 18 relative to the outercasing surface 110, and thus relative to the femur.

With continuing reference to FIGS. 10A-10B, it should be appreciated amethod can be provided for fabricating the femoral prostheses 10 thateach includes the core body 34 that is configured to be inserted intothe medullary canal 21 of the femur 23. The femoral prostheses 10 and inparticular the stem components 16, can include substantially equallysized and shaped cores 31, but disposed in different locations in therespective outer casings 33 along the central neck axis 29 so as todefine different respective neck offsets 164. In this regard, the neckoffset 164 can be referred to as a selectable neck offset. A method offabricating the femoral prosthesis 10 can include the step of applyingthe porous casing 33 onto the core body 34 so as to define the innercasing surface 108 that faces the core body 34 and the outer casingsurface 110 opposite the inner casing surface 108, such that the neck 28is offset from the casing 33 as desired.

The method can include the step of manufacturing a first porous casing33 onto a first core body 34 so as to define a first femoral prosthesis10 whereby 1) a first neck 28 extends out with respect to the proximalend of the first core body 34 at a fixed neck angle 40, and 2) the neck28 defines a fixed distance to the core body 34. The first porous casing33 defines a first inner casing surface 108 that faces the first corebody 34 and a first outer casing surface 110 opposite the first innercasing surface 108. The first femoral prosthesis can define the firstneck offset 164 a as described above.

The method can include the step of manufacturing a second porous casing33 onto a second core body 34 so as to define a first second femoralprosthesis 10 whereby 1) a second neck 28 extends out with respect tothe proximal end of the second core body 34 at the fixed neck angle 40,and 2) the second neck 28 defines the fixed distance to the core body34. The second porous casing 33 defines a second inner casing surface108 that faces the second core body 34 and a second outer casing surface110 opposite the second inner casing surface 108. The second outercasing surface 110 can be substantially equally sized and shaped withrespect to the first outer casing surface 110. The second femoralprosthesis 10 can define the second neck offset 164 b as describedabove. Alternatively or additionally, the first femoral prosthesis 10can include either or both of the first selectable neck angle 162 a andthe first rotational position 166 a described above. Alternatively oradditionally still, the first femoral prosthesis 10 can include eitheror both of the first selectable neck angle 162 a and the firstrotational position 166 a described above.

With continuing reference to FIGS. 10A-10B, while the neck offset 164provides one way to measure the different positions of substantiallyidentical cores 31, in still other examples the different positions canbe defined by an offset from the casing 33, and in particular from theproximal casing end 151, to a portion 173 of the core 31 that includesthe neck 28 and the trunnion 30. The portion 173 of the core 31 canfurther include the shoulder 32. As described above with respect to theneck offset 164, the offset from the casing 33 to the portion of thecore 31 can be oriented along a direction substantially parallel to thecentral neck axis 29.

In this regard, it is recognized that a plurality of femoral prosthesescan be designed and manufactured having substantially identical corebodies 34 that define different geometries when surrounded by respectivecasings 33. The casings 33 can be additively manufactured onto the corebodies 34. Alternatively, the casings 33 can be separately fabricated soas to receive the respective core bodies 34. The geometries can beselected as one or more up to all of the first selectable neck angle 162a (see FIGS. 7B-7C), the second selectable neck angle 162 b (see FIGS.8A-8C), the rotational position 166 and resulting first and secondangles of rotation 168 a and 168 b (see FIGS. 9A-9C), and the first andsecond neck offsets 164 a and 164 b (see FIGS. 10A-10B).

Referring now to FIG. 11 , a method 170 for performing a hiparthroplasty is shown. The method 170 includes step 172, in which anorthopaedic surgeon, or other member of a surgical team, may resect aproximal end of a patient's femur 23 to form the surgically preparedplanar proximal surface 90. As described above, the femoral prosthesis10 may include a stem component 16 and a femoral head component 18.Depending on the needs of the patient, the surgeon may also include thecollar 14, including one of the stabilizing collar 22 or trochantercollar 24 in the femoral prosthesis 10. Alternatively, the femoralprostheses as fabricated can include the collar 14. In some embodiments,such as the case in some revision hip arthroplasties, an orthopaedicsurgeon will also prepare medial surface of a trochanter of thepatient's femur 23. At step 174, the orthopaedic surgeon selects a stemcomponent 16 and a femoral head component 18 based on surgicalparameters determined before the surgical operation began andintra-operative data determined during the surgical operation. Forinstance, the stem component 16 can be any one of the first stemcomponent that includes the first core body encased by the casing 33,the second stem component that includes the second core body encased bythe casing 33, and the third stem component that includes the secondcore body encased by the casing 33 as described above with respect toFIGS. 7A-7C.

At step 176, the orthopaedic surgeon may insert a broach through theplanar proximal surface 90 of the patient's femur 23 to define apassageway in the medullary canal 21 of the patient's femur 23 sized toreceive the selected femoral stem component 16 (see FIGS. 2A-2B). Thesize of the broach used by the orthopaedic surgeon is determined basedon the size of the selected femoral component.

At step 178, the orthopaedic surgeon determines whether the femoralprosthesis 10 requires more stability than what is provided by the stemcomponent 16 alone. If the femoral prosthesis 10 does not indicatedesirability for additional stability, the surgeon may continue to step174 in which the stem component 16 and the femoral head component 18 areimplanted in the patient's femur 23. If additional stability is desired,the surgeon continues to step 180 in which the surgeon selects a collarfrom the plurality of collars 14 to couple to the stem component 16.Alternatively, the surgeon can select a femoral prosthesis that wasmanufactured with a collar 14. Each of the collars of the plurality ofcollars includes the inferior surface 103 (see FIG. 2A) configured toengage the planar proximal surface 90 of the patient's femur 23. Theplurality of collars 14 may include a number of different types ofcollars configured to provide different types of stability. For example,the stabilizing collar 22 includes a platform that provides a largesurface area to engage the planar proximal surface 90 of the patient'sfemur 23. In another example, the trochanter collar 24 includes anabutment member 104 configured to couple a trochanter of the patient'sfemur 23 to the femoral prosthetic assembly.

At step 182, the orthopaedic surgeon may secure the selected collar tothe stem component 16 such that the inferior surface 103 of the collarextends transversely to the central core body axis 39. At step 184, oncethe selected collar 14 is secured in a fixed position relative to thestem component 16, the assembled femoral prosthesis 10 is positioned andimplanted in the patient's femur 23 such that the inferior surface 103of the selected collar engages with the planar proximal surface 90 ofthe patient's femur 23.

While the disclosure has been illustrated and described in detail in thedrawings and foregoing description, such an illustration and descriptionis to be considered as exemplary and not restrictive in character, itbeing understood that only illustrative embodiments have been shown anddescribed and that all changes and modifications that come within thespirit of the disclosure are desired to be protected.

There are a plurality of advantages of the present disclosure arisingfrom the various features of the method, apparatus, and system describedherein. It will be noted that alternative embodiments of the method,apparatus, and system of the present disclosure may not include all ofthe features described yet still benefit from at least some of theadvantages of such features. Those of ordinary skill in the art mayreadily devise their own implementations of the method, apparatus, andsystem that incorporate one or more of the features of the presentinvention and fall within the spirit and scope of the present disclosureas defined by the appended claims.

What is claimed is:
 1. A femoral prosthesis comprising: an elongate corebody that extends along a central core body axis from a proximal corebody end to a distal core body end opposite the proximal core body end,the core body extending from the proximal core body end to the distalcore body end, wherein the core body is configured to be received in amedullary canal of a femur; a neck that extends out with respect to theproximal core body end; and a porous casing that encases at least aportion of the core body, wherein the porous casing defines an innercasing surface that faces the core body and an outer casing surfaceopposite the inner casing surface, wherein the inner surface of theporous casing extends along a central inner casing axis that issubstantially coincident with the central core body axis, and the outersurface of the porous casing extends along a central outer casing axisthat intersects the central inner casing axis within an outer perimeterof the core body with respect to a side elevation view of the stemcomponent that includes the proximal core body end and the distal corebody end.
 2. The femoral prosthesis of claim 1, wherein the sideelevation view further includes a medial core body side of the core bodyand a lateral core body side of the core body.
 3. The femoral prosthesisof claim 1, wherein the side elevation view further includes an anteriorcore body side and a posterior core body side that is opposite theanterior core body side, wherein the anterior and posterior core bodysides each extend from a medial core body side of the core body to alateral core body side of the core body.
 4. The femoral prosthesis ofclaim 1, the porous casing is an additively manufactured porous casing.5. The femoral prosthesis of claim 1, further comprising a porous collarthat is configured to extend out with respect to the neck in apredetermined direction.
 6. The femoral prosthesis of claim 1, whereinthe neck extends out with respect to the core body along a central neckaxis that defines a fixed neck angle with respect to the central corebody axis, and the central neck axis defines a selectable neck anglewith respect to the central outer casing axis, wherein the selectableneck angle is different than the fixed neck angle.
 7. The femoralprosthesis of claim 1, wherein the porous casing further defines arotational position of the core body relative to the outer casingsurface about the central core body axis.
 8. The femoral prosthesis ofclaim 1, wherein the outer casing surface is nonparallel with respect tothe inner casing surface.
 9. The femoral prosthesis of claim 8, whereinthe porous casing defines a thickness from the inner casing surface tothe outer casing surface, the thickness at a first side of the porouscasing increases as the casing extends in a distal direction from theproximal core body end to the distal core body end, and the thickness ata second side of the porous casing decreases as the casing extends inthe distal direction, and the second side is opposite the first side.10. The femoral prosthesis of claim 9, wherein the first side defines amedial side of the porous casing, and the second side defines a lateralside of the porous casing.
 11. The femoral prosthesis of claim 9,wherein the first side defines an anterior side of the porous casing,and the second side defines a posterior side of the porous casing.